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Atomic layer deposition (ALD) of SnO2 thin films from SnI4 and either H2O2 or O2 on the α-Al203(1 1- 2) substrates is
studied. Reactor temperature is varied from 100 to 750 °C. X-ray diffaction, x-ray reflection, x-ray fluorescence, x-ray
photoelectron spectroscopy, reflection high-energy electron diffraction, and UV-visible spectroscopy are used to obtain
the growth and structural data. The SnI4-H202 precursor pair brings forth the film growth even at temperatures as low as
100°C with a wholly amorphous outcome up to 150°C. For the pair SnI4-02, the films grown nearby the process
initiation temperature of 400°C are also amorphous. When the temperature is raised respectively above 250 and 500°C,
both pairs make epitaxial growth happen, generally in three-dimensional mode. Exceptionally, in a limited range of
grown thicknesses in the proximity of 50 nm, the growth from SnI4 and O2 at 750°C appears to be driven by the
predominantly two-dimensional nucleation, as the films grow extremely flat. The SnI4-02 precursor pair gives at 600-
750°C the highest growth per cycle of about 0.085 nm. The epitaxially grown tetragonal (cassiterite) films are (1 0 1)-
oriented. The iodine contamination in them is below 0.1%. All the film-substrate structures are highly transparent in the
visible region.
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